In the past, there have been used an optical coherent tomography (OCT) apparatus (see, for example, Japanese Unexamined Patent Publication No. 2005-196080) and an optical frequency domain imaging (OFDI) apparatus utilizing wavelength sweep, which is an improved type of apparatus for a diagnosis of arteriosclerosis, for a diagnosis before operation at the time of treatment inside a blood vessel depending on a high functional catheter such as a balloon catheter, a stent and the like or to confirm the result after an operation (hereinafter, in the present specification, the optical coherent tomography (OCT) apparatus and the optical frequency domain imaging (OFDI) apparatus utilizing wavelength sweep will be generically referred to as “optical imaging diagnostic apparatus”).
In the optical imaging diagnostic apparatus, an optical probe unit inserted with an imaging core which is attached with an optical lens and an optical mirror (transmission and receiving unit) at a distal end of an optical fiber is inserted into a blood vessel, and a radial scan in a blood vessel is carried out by emitting a measurement light into the blood vessel from the transmitting and receiving unit at the distal end while rotating the imaging core and concurrently, by receiving a reflected light from a biological tissue. Then, an interference signal is generated by making the light-received reflected light and a reference light interfere with each other, and a cross-sectional image of the blood vessel is visualized based on the generated interference signal.
Here, for the radial scan of the imaging core, a motor drive apparatus referred to as a scanner & pull-back unit is generally utilized. The scanner & pull-back unit is constituted by a scanner unit and a pull-back unit, the scanner unit is mounted further with an optical probe unit detachably, and also, there are provided a rotation unit for rotating the imaging core inserted in the mounted optical probe unit and a fixation unit which repeats transmission of the measurement light and reception of the reflected light with respect to the rotating imaging core.
Then, the transmission and reception of the measurement light and the reflected light between the rotation unit and the fixation unit is usually carried out through collimator lenses respectively provided in the rotation unit and the fixation unit. Specifically, the measurement light emanated from the collimator lens provided in the fixation unit is light-received by the collimator lens provided in the rotation unit and the reflected light emanated from the collimator lens provided in the rotation unit is light-received by the collimator lens provided in the fixation unit.
Consequently, in order that an optical imaging apparatus for diagnosis visualizes a cross-sectional image of high image quality, it is important to suppress loss of the measurement light and the reflected light (these are referred to collectively as an optical signal) as much as possible between the two collimator lenses and for that purpose, it becomes indispensable to adjust the optical axes of both the collimator lenses highly accurately (such that the optical axis center tolerance and the optical axis angle tolerance fall within a predetermined range).
However, in the case of a conventional scanner & pull-back unit, a collimator lens was fixed, by using an adhesive agent, to a hollow tubular member for fixing the collimator lens. Consequently, the optical axis of the collimator lens which was adjusted before the hardening of the adhesive agent sometimes deviated due to the hardening and shrinkage of the adhesive agent. Further, in the conventional scanner & pull-back unit, once the collimator lens was fixed to the tubular member in this manner, it was difficult to fine-adjust the optical axis center and the optical axis angle anew. Due to such a fact, in an optical imaging apparatus for diagnosis, there is a demand for provision of a scanner & pull-back unit (motor drive apparatus) capable of highly accurately adjusting the optical axis between the collimator lenses in the rotation unit and in the fixation unit.